Recurring friendly character, principally in Batman stories, who was responsible for transporting heroes, at their request, back in time. Think of him as the Doc Brown of the pre-Crisis DCU. Oddly, he doesn't appear to have ever learned any hero's secret identity.

It is currently unclear whether he existed on both Earths, but his character was not a part of the Crisis and hasn't been seen in the modern age.

Recurring friendly character, principally in Batman stories, who was responsible for transporting heroes, at their request, back in time. Think of him as the Doc Brown of the pre-Crisis DCU. Oddly, he doesn't appear to have ever learned any hero's secret identity.

It is currently unclear whether he existed on both Earths, but his character was not a part of the Crisis and hasn't been seen in the modern age.

He was later posited to be the mentor of Zan and Jayna—the Wonder Twins.